The present invention relates to coloring, shading or tinting contact lenses and, more particularly, relates to a lens structure having an interior opaque iris section for partially obscuring, at a minimum, the color of the natural iris of the wearer's eye and a pigmented portion located on the front surface of the lens for providing an appearance of color to the iris portion. Other aspects of the invention relate to methods of manufacturing such a lens.
Recently, there has been a great deal of interest in contact lenses which change or otherwise alter the color of the iris of the wearer's eye. In attempts to meet this demand, various lens structures have been proposed. For example, U.S. Pat. Nos. 3,557,261 and 3,679,504 to Wichterle et al. discloses a method for manufacturing contact lenses having a colored pattern enclosed between at least two layers of soft, transparent hydrogel material. U.S. Pat. No. 3,536,386 to Spivack also shows an imprinted portion sandwiched between two layers of lens material for creating the appearance of alternative eye color. U.S. Pat. No. 4 460 523 to Neefe discloses a method of making contact lenses which change eye color by employing small light reflecting particles imbedded in a colored transparent matrix. Canadian Patent No. 710,230 to Rich and U.S. Pat. No. 4,559,059 to Su disclose lenses having tinting on their front surfaces. Other patents relating to this area are U.S. Pat. No. 4,582,402 to Knapp, and U.S. Pat. Nos. 4,472,327; 4,615,593 and 4,701,038, all to Neefe.
The above examples and other known tinted contact lenses suffer from a substantial drawback. While such lenses are capable of enhancing existing eye color or changing the color of light-colored eyes, they are incapable of causing significant color changes. For example, it is difficult to change a natural dark brown eye color to pale blue using presently known lenses, because the lighter blue pigments cannot mask the darker, brown pigments. As a result, a desired color change is often impossible to achieve. Also, previous attempts at masking or changing the natural iris color have resulted in a flat, unnatural appearance of the eyes when the contact lenses are worn.
Furthermore, it is common practice for lenses to be tinted by the manufacturer and merely fitted by the local practitioner. As a result, the choice of colors available to the wearer is subject to the manufacturer's choice of product and is limited by the ability of the practitioner to maintain an inventory of a large number of lenses having an array of colors.
There exists a need, therefore, for a natural looking contact lens capable of causing significant changes in the appearance of the eye color of the wearer, and, more particularly, changing a dark eye color to a lighter color.
There also exists a need for such a contact lens which can be tinted by the local practitioner at the point of sale.
There exists a further need for a method of producing such a lens which is inexpensive and efficient.